PRODUCTION OF STEEL SHEET EXCELLENT IN DEEP DRAWABILITY, USING INVERSE TRANSFORMATION

摘要

PROBLEM TO BE SOLVED: To provide a high strength hot rolled steel sheet free from deterioration in productivity at the time of continuous hot rolling and excellent in deep drawability, a high strength cold rolled steel sheet, and a galvanized steel sheet, and their production. ;SOLUTION: The steel sheet excellent in deep drawability can be produced by using a steel having a composition containing, by weight, ≤0.05% C, ≤0.01% N, and either or both of ≤0.1% Ti and ≤0.1% Nb, starting finish rolling of the steel in the temp. region between (Ar₃ transformation point-100°C) and the Ar₃ transformation point, elevating the temp. of the resultant steel sheet up to a temp. not lower than the Ac₃ transformation point by means of temp. increase due to working by rolling and/or recuperation of the steel sheet to subject ferrite (α) to inverse transformation into austenite (γ), transforming austenite (γ) into ferrite (α) by subsequent cooling, and coiling the steel sheet at ≥300°C.;COPYRIGHT: (C)1999,JPO